Synthesis and characterization of a Dion–Jacobson two-dimensional perovskite

Two-dimensional (2D) metal halide perovskites feature several specific advantages over others 2D materials, such as facile wet chemical synthesis and layers exfoliation, high composition combination especially the choice of organic cations as well as 2D phase, excellent confinement for exciton. In this paper, we present a fundamental study of diaminonaphthalene lead iodide (DANPI) perovskite, a Dion–Jacobson 2D perovskite based on divalent cation organic spacer 1,5-diaminonaphthalene. We report its material synthesis, optical and structural characterization as well as DFT calculations. Hydro-iodic acid-based wet chemistry was used to prepare DANPI crystals and, by cast-capping, thin films as well. Both DANPI materials show a dominant emission peak at about 519 nm with a full width at half-maximum as small as 14 nm. This peak coincides with the absorption edge of the material at 510 nm (2.43 eV) which suggests an exciton-related recombination process. According to single-crystal X-ray diffraction measurements the crystal structure could be either monoclinic P21/c or tetragonal P4212. DFT calculations including spin–orbit coupling show that the DANPI band gap is direct, with a valence band of s-symmetry and a conduction band of p-symmetry.

A dominant emission peak at about 519 nm with a full width at half-maximum as small as 14 nm.